An SSID is the name of a wireless local area network (WLAN). All wireless devices on a WLAN must employ the same SSID in order to communicate with each other.

The SSID on wireless clients can be set either manually, by entering the SSID into the client network settings, or automatically, by leaving the SSID unspecified or blank. A network administrator often uses a public SSID, that is set on the access point and broadcast to all wireless devices in range. Some newer wireless access points disable the automatic SSID broadcast feature in an attempt to improve network security.

SSIDs are case sensitive text strings. The SSID is a sequence of alphanumeric characters (letters or numbers). SSIDs have a maximum length of 32 characters.

Wardrivers sometimes scan for the SSIDs being broadcast by wireless LANs, then set that SSID on their client to attempt to join that WLAN. Knowing the SSID name does not necessarily mean that rogue clients will be able to join the network. It depends on how the network administrator has configured their WLAN, particularly WEP